Although aircrafts can use reverse thrust to push themselves backwards on the ground, the jet blast or the prop wash resulting from the reverse thrust can cause damage to an airport terminal building or equipment. Also, aircraft engines close to the ground may blow sand and debris forward and then suck it back into the aircraft engine, causing damage to the aircraft engine. Therefore, using external power to push the aircraft backwards is often preferred over using the reverse thrust of the aircraft. This procedure of pushing an aircraft backwards using external power is referred to as ‘pushback’.
Typically, pushback operations use a vehicle, such as a pushback tractor, in conjunction with a tow bar as illustrated in the example embodiment of FIG. 1. In particular, as illustrated in FIG. 1, one end of the tow bar 102 may be coupled to a nose landing gear 112 of the aircraft 110 while the other end of the tow bar 102 may be coupled to the vehicle 106. Once the tow bar 102 is coupled to both the aircraft 110 and the vehicle 106, a driver may operate/steer the vehicle 106 to push the aircraft back by leveraging the tow bar 102. Once the pushback operation is completed, the tow bar 102 is disconnected and the vehicle 102 is driven away from the aircraft 110 to clear the aircraft 110 for taxiing.
Conventional technology includes disconnecting the tow bar using a three point disconnect operation as illustrated in FIG. 1. In particular, as illustrated in FIG. 1, the three point disconnect operation includes three steps for disconnecting the tow bar after pushback. First, the tow bar 102 is disconnected from the vehicle 106 and the vehicle 106 is driven to a short distance away from the aircraft 110 (Step 150). Then, the tow bar 102 is disconnected from the nose landing gear 112 of the aircraft 110 (Step 160). At this point, the tow bar 102 remains disconnected from both the vehicle 106 and the aircraft 110, and the tow bar 102 is manually pulled on its carry wheels 104 towards the vehicle 106 (Step 170). Finally, the tow bar 102 is connected back to the vehicle 106, and the vehicle 106 is driven away with the tow bar 102 to ready the aircraft 110 for taxiing. The conventional three point disconnect operation is time intensive as it requires carefully disconnecting the tow bar 102 on each end and then reconnecting one end back to the vehicle 106. The time intensive nature of the three point disconnect operation may cause aircraft departure delay. Further, since the aircraft engine is operational during the pushback as well as tow bar 102 disconnect operation, a longer disconnect time will result in unproductive and undesirable consumption of aircraft fuel which is very expensive.
An alternative to the three-point disconnect operation may include a single point disconnect operation which includes only one step where the tow bar 102 is disconnected from the nose landing gear 112 while the tow bar 102 remains coupled to the vehicle 106, as illustrated in FIG. 2. That is, in this prior single point disconnect operation, once the aircraft 110 is pushed back, the tow bar 102 is not disconnected from the vehicle 106 as in the case of the three-point mechanism. Instead, in the prior single point disconnect operation, the tow bar 102 is only disconnected from the nose landing gear 112 of the aircraft 110 while the other end of the tow bar 102 remains coupled to the vehicle 106 (Step 260). The single point disconnect operation saves significant time over the three point disconnect operation, since the single point disconnect operation includes only one step, i.e., disconnect the tow bar 102 from the nose landing gear 112. For example, the single point disconnect operation saves approximately two and a half minutes per push on average and allows the aircraft to depart quicker after the pushback operation, which in turn leads to substantial fuel savings, cost savings, and quicker departure.
While single point disconnect operation may be more efficient compared to three point disconnect operation, improper disconnection of the tow bar 102 using the prior single point disconnect operation may result in significant injury to the ground crew and/or damage to the aircraft, e.g., damage to the aircraft nose landing gear as illustrated in FIGS. 3 and 4.
In one example, as illustrated in FIG. 3A, after the pushback operation, the angle of the tow bar 102 respective to the surface 404 of the vehicle 106 may exceed a threshold limit. The term ‘surface of the vehicle,’ as used herein generally refers to a surface (of the vehicle) to which the tow bar is coupled. For example, if the tow bar is coupled to a back side of the vehicle, the surface of the vehicle may refer to a rear surface. The term ‘angle of the tow bar respective to the surface of the vehicle,’ as used herein may refer to a horizontal angle formed by a longitudinal axis of the tow bar 102, i.e., the axis along the length of the tow bar, with respect to a plane passing through a longitudinal axis and a vertical axis of the vehicle, provided the tow bar 102 is coupled to either the front side or rear side of the vehicle. Herein, the plane passing through the longitudinal axis and the vertical axis of the vehicle 106 may be referred to as ‘longitudinal plane of the vehicle’. Further, the term ‘longitudinal axis of the vehicle,’ as used herein may generally refer to an axis that is parallel to the ground, extends along the length of the vehicle (e.g., a pushback tractor/tug), and symmetrically divides the vehicle into a right half and left half. The lateral axis of the vehicle is orthogonal to the longitudinal axis and is also parallel to the ground. The term ‘vertical axis of the vehicle,’ as used herein generally refers to an axis of the vehicle that is orthogonal to both the longitudinal and lateral axis of the vehicle 106. Further, the term ‘horizontal angle,’ and used herein may generally refer to an angle between two lines on a substantially horizontal plane or a plane passing through the longitudinal axis and the lateral axis of the vehicle and substantially parallel to the ground. The longitudinal axis 340 of the vehicle 106, the lateral axis 350 of the vehicle 106, the vertical axis 360 of the vehicle 106, and the longitudinal axis of the tow bar 102 are illustrated for reference in FIG. 3C. The term ‘longitudinal axis of the tow bar,’ generally refers to an axis through the length of the tow bar.
When the angle formed by a longitudinal axis of the tow bar 102 with respect to a plane passing through a longitudinal plane of the vehicle exceeds a threshold limit, the tow bar 102 may pivot on the carry wheels 104 and strike the aircraft wheel 114 responsive to disconnecting the tow bar 102 from the nose landing gear 112 of the aircraft 110, as illustrated by reference numerals 304a and 304b in FIG. 3B. That is, too much departure angle between the tow bar 102 and the surface 404 of the vehicle 106 may cause the tow bar head to come in contact with the nose landing gear 112 and/or the nose landing wheel 114 of the aircraft 110 and result in significant damage.
In another example illustrated in FIG. 4A, after a pushback operation, the wheels 108 associated with steering of the vehicle 106 (herein ‘steering wheels 108’) may not be straight, i.e., the direction of the wheels 108 may not be substantially parallel to the longitudinal axis of the vehicle 106. Similar to an improper alignment of the tow bar 102, if the steering wheels 108 of the vehicle 106 are not straight, the tow bar 102 may pivot on the carry wheels 104 and the head of the tow bar 102 striking the nose landing gear 112 and/or the nose landing wheel 114 of the aircraft responsive to disconnecting the tow bar 102 from the nose landing gear 112 of the aircraft 110 and moving the vehicle 106 away from the aircraft 110. Damage to the nose landing gear 112 and/or nose landing wheel 114 can result in a cancelled flight which may be costly both financially and in regards with passenger experience. Therefore, there is a need for a technology that provides a safe and efficient solution for single point disconnect of a tow bar and subsequent departure.